Polishing pad, method for manufacturing polishing pad and polishing apparatus

ABSTRACT

The present disclosure relates to a polishing pad including a polishing layer. The polishing layer defines a plurality of foaming pores, and a diameter of each of the foaming pores is 1 μm to 10 μm. The present disclosure also relates to a method for manufacturing a polishing pad and a polishing apparatus.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates to a polishing pad having small pores, a method for manufacturing the polishing pad, and a polishing apparatus.

2. Description of the Related Art

A polishing process generally refers to a wear control for a preliminary coarse surface in a process of chemical mechanical polishing (CMP), which makes slurry containing fine particles evenly dispersed on an upper surface of a polishing pad, and at the same time places a substrate against the polishing pad and then rubs the substrate repeatedly with the polishing pad in a regular motion. The substrate may be a semiconductor, a storage medium substrate, an integrated circuit, an LCD flat-panel glass, an optical glass or a photoelectric panel. During the polishing process, a polishing pad must be used to rub the substrate, thus the quality of the polishing pad directly influences the polishing effect to the substrate.

To achieve favorable polishing result, the polishing pad usually has plural pores for retaining slurry therein. FIGS. 1A and 1B respectively show a top view and a cross sectional view of a conventional polishing pad. The polishing pad has plural pores. A width of an opening of the pores is about 100 μm, and a depth of the pores can be as large as about 500 μm. Due to the large size of the pores of the conventional polishing pad, residues formed during the polishing process, such as contaminants or abrasive aggregates, may clog the pores, thus resulting in damage to the substrate.

SUMMARY

In some embodiments, a polishing pad includes a polishing layer. The polishing layer defines a plurality of foaming pores, and a diameter of each of the foaming pores is in the range of 1 μm to 10 μm.

In some embodiments, a method for manufacturing the aforementioned polishing pad includes: (a) providing a base layer; (b) forming a resin foam on the base layer, wherein the resin foam comprises a polishing layer and a nap layer, the polishing layer defines a plurality of foaming pores, and a diameter of each of the foaming pores is in the range of 1 μm to 10 μm; and (c) removing the nap layer.

In some embodiments, a polishing apparatus includes a polishing plate, a substrate, the aforementioned polishing pad and a slurry. The polishing pad is adhered on the polishing plate for polishing the substrate. The slurry contacts the substrate for polishing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows an enlarged top view of a conventional polishing pad.

FIG. 1B shows an enlarged cross sectional view of the conventional polishing pad.

FIG. 2A illustrates a cross sectional view of a polishing pad according to an embodiment of the present disclosure.

FIG. 2B illustrates a cross sectional view of a polishing pad according to another embodiment of the present disclosure.

FIG. 3A shows a scanning electron microscope (SEM) image at 1,000× magnification of a top view of a polishing pad according to an embodiment of the present disclosure.

FIG. 3B shows a SEM image at 1,000× magnification of a cross sectional view of the polishing pad according to an embodiment of the present disclosure.

FIG. 4A illustrates one or more stages for manufacturing a polishing pad according to an embodiment of the present disclosure.

FIG. 4B illustrates one or more stages for manufacturing a polishing pad according to an embodiment of the present disclosure.

FIG. 4C shows a SEM image at 2,600× magnification of a cross sectional view of a polishing layer of a resin foam according to an embodiment of the present disclosure.

FIG. 4D illustrates one or more stages for manufacturing a polishing pad according to an embodiment of the present disclosure.

FIG. 5 illustrates a cross sectional view of a polishing apparatus according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure provides for a polishing pad, including: a polishing layer, defining a plurality of foaming pores, and a diameter of each of the foaming pores is in the range of 1 μm to 10 μm.

FIG. 2A illustrates a cross sectional view of a polishing pad 1 according to an embodiment of the present disclosure. The polishing pad 1 includes a polishing layer 11. The polishing layer 11 includes or defines a plurality of foaming pores 12, and a diameter of each of the foaming pores 12 is in the range of 1 μm to 10 μm.

The term “polishing pad” according to the present disclosure refers to a pad adapted for abutting against a substrate to be polished in a process of chemical mechanical polishing. The polishing pad rubs the substrate to be polished repeatedly in a regular motion with the cooperation of slurry containing small particles, so as to wear a preliminary coarse surface of the substrate into a smooth surface.

The polishing layer 11 according to the present disclosure refers to an element of a polishing pad, which element is adapted for contacting with and rubbing the substrate to be polished. That is, the polishing layer is the element which actually executes polishing with the cooperation of the slurry. The polishing layer 11 includes or defines the foaming pores 12, and a diameter of each of the foaming pores 12 is in the range of 1 μm to 10 μm, preferably in the range of 1 μm to 8 μm, and more preferably in the range of 1 μm to 5 μm.

Specifically, the polishing layer 11 may be made of a resin foam, and the foaming pores 12 may be pores defined by the resin foam. The term “resin foam (foaming resin)” according to the present disclosure refers to a material containing a thermoplastic resin and a thermodecomposing foaming agent. Preferably, the resin includes at least one selected from a group consisting of polyurethane, polyolefin, polycarbonate, polyvinyl alcohol, nylon, elastic rubber, polystyrene, poly aromatic molecules, fluorine-containing polymer, polyimide, crosslinked polyurethane, crosslinked polyolefin, polyether, polyester, polyacrylate, elastic polyethylene, polytetrafluoroethene, poly (ethylene terephthalate), poly aromatic amide, polyarylalkene, polymethyl methacrylate, a copolymer thereof, a block copolymer thereof, a mixture thereof, and a blend thereof.

A manner of foaming the resin foam according to the present disclosure can be chemically foaming or physically foaming. The chemically foaming manner uses an agent capable of conducting a chemical reaction to yield gas, with the gas evenly distributed in the resin composition. In another aspect, the physically foaming manner includes infiltrating gas into the resin composition, and making the gas evenly distributed in the resin composition by stirring.

As mentioned above, the foaming pores 12 may be pores defined by the resin foam. In addition, the foaming pores 12 are preferably continuous pores. The term “continuous pores” according to the present disclosure refers to at least two pores connecting to or in communication with each other to form a pore system similar to an ant nest, which is beneficial to flow of the slurry, distribution of the polishing particles and removal of polishing residues.

Preferably, a material of the polishing layer 11 may be polyurethane. Said polyurethane may be formed through a wet process. The diameter of the foaming pores 12 may be precisely controlled by the wet process, and the foaming pores 12 may be formed as continuous pores.

In another aspect, the polishing layer 11 has a polishing surface 13, and the foaming pores 12 are exposed on the polishing surface 13. Some of the foaming pores 12 may be recessed form the polishing surface 13. A distribution density of the foaming pores 12 on the polishing surface 13 is in the range of 15,000/mm² to 20,000/mm².

In the polishing pad 1 according to the present disclosure, since the diameter of the foaming pores 12 of the polishing layer 11 is not greater than 10 μm, residues formed during the polishing process, such as contaminants and abrasive aggregates, may not be retained in or clog the foaming pores 12, thus can avoid damage to the substrate to be polished. Besides, the continuous foaming pores 12 can assist or facilitate flow of the slurry, thus improving removal of the polishing residues.

FIG. 2B illustrates a cross sectional view of a polishing pad 1 b according to another embodiment of the present disclosure. The polishing pad 1 b shown in FIG. 2B is similar to the polishing pad 1 shown in FIG. 2A, while the polishing pad 1 b further includes a base layer 14, and the polishing layer 11 is attached to the base layer 14. The base layer 14 may be a nonwoven fabric, a nonwoven fabric impregnated with polyurethane, or a polyethylene terephthalate (PET) film. In an embodiment, the base layer 14 may provide for buffering purpose.

The term “nonwoven fabric” according to the present disclosure refers to a sheet, web or bat manufactured by directionally or randomly oriented fibers, bonded by friction, and/or cohesion and/or adhesion, excluding paper or products which are woven, knitted, tufted stitch bonded incorporating binding yarns or filaments, or felted by wet milling, whether or not additionally needled. The fibers may be of natural or man-made origin. They may be staple or continuous filaments or may be formed in situ. Depending on the method for forming the web, the nonwoven fabric usually includes a composite nonwoven fabric, a needle-punched nonwoven fabric, a melt-blown nonwoven fabric, a spun bonded nonwoven fabric, a dry-laid nonwoven fabric, a wet-laid nonwoven fabric, a stitch-bonded nonwoven fabric, or a spun lace nonwoven fabric. Compared with a woven fabric, a nonwoven fabric has a better material property.

In a preferred embodiment of the present disclosure, the base layer 14 may be a support or carrier for forming the polishing layer 11 thereon. For example, a resin foam may be formed on the base layer 14. The resin foam may include or define the foaming pores 12. Then, a grinding or cutting process may be conducted to remove a predetermined thickness of the resin foam, such that the polishing surface 13 is formed with the foaming pores 12 exposed therefrom.

FIGS. 3A and 3B respectively show SEM images at 1,000× magnification of a top view and a cross sectional view of the polishing pad according to an embodiment of the present disclosure. As shown in FIGS. 3A and 3B, the foaming pores of the polishing pad of the present disclosure has a diameter with a maximum value of about 6.40 μm, a minimum value of about 3.30 μm, and an average value of about 4.11 μm. Besides, the foaming pores are continuous pores.

The present disclosure further provides for a method for manufacturing the aforementioned polishing pad, including:

(a) providing a base layer;

(b) forming a resin foam on the base layer, wherein the resin foam comprises a polishing layer and a nap layer, the polishing layer comprises or defines a plurality of foaming pores, and a diameter of each of the foaming pores is in the range of 1 μm to 10 μm; and

(c) removing the nap layer.

FIGS. 4A to 4D illustrate stages for manufacturing the polishing pad 1 or the polishing pad 1 b according to an embodiment of the present disclosure.

FIG. 4A illustrates the step (a) of providing a base layer 14. The base layer 14 may be a nonwoven fabric or a PET film, as described above.

FIB. 4B illustrates the step (b) of forming a resin foam 3 on the base layer 14. The resin foam 3 includes a polishing layer 31 and a nap layer 34. The polishing layer 31 includes or defines a plurality of foaming pores 32, and a diameter of each of the foaming pores 32 is in the range of 1 μm to 10 μm. In the step (b), the resin foam is preferably made of polyurethane, and formed through a wet process, such that the diameter of the foaming pores 32 can be precisely controlled and the foaming pores 32 can be continuous. In addition, the base layer 14 is preferably a nonwoven fabric, such that the shape of the foaming pores 32 of the resin foam 3 can be controlled by adjusting the density and the water content (or moisture content) of the nonwoven fabric.

For example, the step (b) may include:

(b1) coating a solution containing a resin material on the base layer;

(b2) curing the resin material to form a resin foam;

(b3) washing the resin foam; and

(b4) drying the resin foam.

In the step (b1), dimethylformamide (DMF) may be used as a solvent for dissolving the resin material. In addition to the solvent, the solution containing the resin material may optionally include additives, such as a surfactant. In an embodiment, a concentration of the resin material in the solution is preferably in the range of 2 wt % to 60 wt %.

In the step (b2), the base layer 14 along with the resin material may be immersed in a coagulation bath, such that the resin material may be cured to form the resin foam 3. The coagulation bath may include about 45 wt % to about 70% DMF in water, preferably about 55 wt % to about 65 wt %, and more preferably about 60 wt %. Optimal curing condition is well known to one of ordinary skill in the art. Preferably, the curing process is conducted at room temperature (about 25° C.) and normal pressure (about 1 atm), and the resin material is immersed in the coagulation bath for about 1 hour to about 5 hours, preferably about 3 hours. Since the solution containing the resin material is coated on the base layer 14 in step (b1), the resin foam 3 is attached to the base layer 14 after the curing process in (b2).

For example, in an embodiment of the present disclosure, the coagulation bath includes about 60 wt % of DMF in water, and the resin material (along with the base layer 14) is immersed in the coagulation bath for about 3 hours to form the resin foam 3. The resin foam 3 includes the polishing layer 31, and the diameter of each of the foaming pores 32 is in the range of 1 μm to 10 μm. A SEM image at 2,600× magnification of a cross sectional view of the polishing layer 31 is shown in FIG. 4C.

In a preferred embodiment of the present disclosure, the method for manufacturing the polishing pad further includes a washing or rinsing step (b3) after the curing step (b2). The rinsing process is conducted for removal of residues and contaminants from the base layer 14 and the resin foam 3. In an embodiment of the present disclosure, the resin foam 3 is rinsed with water and optionally passes through mangle (rollers). Optimal rinsing condition is well known to one of ordinary skill in the art. Preferably, the base layer 14 and the resin foam 3 are rinsed with water at a temperature of 50° C. to 90° C., and pass through the mangle for several times.

In the step (b4), the drying process is conducted for removal of solvent or rinsing water from the base layer 14 and the resin foam 3. Optimal drying condition is well known to one of ordinary skill in the art. In an embodiment, the resin foam 3 is air-dried at a temperature of 100° C. to 160° C.

As shown in FIG. 4B, the resin foam 3 may be formed on the base layer 14 thorough the wet process as described above. The resin foam 3 includes a polishing layer 31 and a nap layer 34 which are formed concurrently. The nap layer 34 has plural holes 341 which are larger in size (e.g., having a diameter or depth greater than that of the foaming pores 32), thus the nap layer 34 must be removed in a later step. The polishing layer 31 has or defines small foaming pores 32, thus is suitable for polishing purpose. Accordingly, after removing the nap layer 34 in step (c), the resin foam 3 forms the polishing layer 11 as shown in FIG. 2B. The polishing layer 11 has a polishing surface 13, and the foaming pores 12 are exposed on the polishing surface 13. The polishing pad 1 b as shown in FIG. 2B is thus formed, which includes the polishing layer 11 and the base layer 14.

In the step (c), the nap layer 34 may be removed by mechanical grinding, such as sand-blasting. Optimal condition for mechanical grinding is well known to one of ordinary skill in the art. In an embodiment, the step (c) may include removing one-tenth ( 1/10) to one-half (½) of a total thickness of the resin foam 3, which ensures that the nap layer 34 is completely removed.

In addition, in an embodiment as shown in FIG. 4D, before the step (c), the method may further include a step (c0) of removing the base layer. Since a binding force between the resin foam 3 and the base layer 14 may increase while the water content (or moisture content) of the resin foam 3 decreases, the base layer 14 is preferably removed immediately after formation of the resin foam 3. Then, the nap layer 34 is removed, and the resin foam 3 forms the polishing layer 11 as shown in FIG. 2A. The polishing layer 11 has a polishing surface 13, and the foaming pores 12 are exposed on the polishing surface 13. The polishing pad 1 as shown in FIG. 2A is thus formed, which includes the polishing layer 11.

The present disclosure also provides for a polishing apparatus, including:

a polishing plate;

a substrate to be polished;

the aforementioned polishing pad, which is adhered on the polishing plate for polishing the substrate; and

a slurry contacting the substrate for polishing.

FIG. 5 illustrates a cross sectional view of a polishing apparatus according to an embodiment of the present disclosure. The polishing apparatus 5 includes a pressure plate 51, a mounting sheet 52, a substrate 53 to be polished, a polishing plate 54, a polishing pad 55 and slurry 56. The polishing pad 55 may be the aforementioned polishing pad 1 or the aforementioned polishing pad 1 b. The pressure plate 51 is positioned opposite to the polishing plate 54. The mounting sheet 52 is adhered to the pressure plate 51 through a backside adhesive (not shown) and is used for carrying and mounting the substrate 53. The polishing pad 55 is mounted on the polishing plate 54 and faces the pressure plate 51 for polishing the substrate 53.

The operation manner of the polishing apparatus 5 is as follows. First, the substrate 53 is mounted to and fixed on the mounting sheet 52. Then, the pressure plate 51 and the polishing plate 54 are rotated along opposite directions, and the pressure plate 51 is simultaneously moved toward the polishing plate 54, such that the polishing pad 55 contacts the surface of the substrate 53. Accordingly, the substrate 53 can be polished by the polishing pad 55 with the continuously supplemented slurry 56.

While embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by persons skilled in the art. It is intended that the present invention is not limited to the particular forms as illustrated, and that all modifications not departing from the spirit and scope of the present invention are within the scope as defined in the following claims. 

What is claimed is:
 1. A polishing pad, comprising: a polishing layer, defining a plurality of foaming pores, wherein a diameter of each of the foaming pores is in the range of 1 μm to 10 μm.
 2. The polishing pad of claim 1, wherein the foaming pores are continuous pores.
 3. The polishing pad of claim 1, wherein the polishing layer has a polishing surface, the foaming pores are exposed on the polishing surface, and a distribution density of the foaming pores on the polishing surface is in the range of 15,000/mm² to 20,000/mm².
 4. The polishing pad of claim 1, wherein a material of the polishing layer includes polyurethane.
 5. The polishing pad of claim 1, further comprising a base layer, wherein the polishing layer is attached to the base layer, and the base layer is a nonwoven fabric or a polyethylene terephthalate film.
 6. A method for manufacturing the polishing pad of claim 1, comprising: (a) providing a base layer; (b) forming a resin foam on the base layer, wherein the resin foam comprises a polishing layer and a nap layer, the polishing layer defines a plurality of foaming pores, and a diameter of each of the foaming pores is in the range of 1 μm to 10 μm; and (c) removing the nap layer.
 7. The method of claim 6, wherein in (a), the base layer is a nonwoven fabric or a polyethylene terephthalate film.
 8. The method of claim 6, wherein (b) comprises forming the resin foam through a wet process.
 9. The method of claim 8, wherein in (b), a material of the resin foam includes polyurethane.
 10. The method of claim 6, wherein in (b), the foaming pores are continuous pores.
 11. The method of claim 6, wherein (c) comprises removing one-tenth to one-half of a thickness of the resin foam.
 12. The method of claim 6, wherein before (c), the method further comprises: (c0) removing the base layer.
 13. A polishing apparatus comprising: a polishing plate; a substrate; the polishing pad of claim 1, which is adhered on the polishing plate for polishing the substrate; and a slurry contacting the substrate for polishing.
 14. The polishing apparatus of claim 13, wherein the foaming pores of the polishing layer of the polishing pad are continuous pores.
 15. The polishing apparatus of claim 13, wherein the polishing layer of the polishing pad has a polishing surface, the foaming pores are exposed on the polishing surface, and a distribution density of the foaming pores on the polishing surface is in the range of 15,000/mm² to 20,000/mm².
 16. The polishing apparatus of claim 13, wherein a material of the polishing layer of the polishing pad includes polyurethane.
 17. The polishing apparatus of claim 13, wherein the polishing pad further comprises a base layer, the polishing layer of the polishing pad is attached to the base layer, and the base layer is a nonwoven fabric or a polyethylene terephthalate film. 